Tilbage til slide -- Tastaturgenvej: 'u'                      functions/eq-sec-degree-var2.c - Illustration af ulovlig anvendelse af en lokal variabel.Lektion 5 - slide 6 : 30
Program 1

#include <stdio.h>
#include <math.h>

/* Find the roots in a * x*x + b * x + c = 0 */
void solveQuadraticEquation(void){
  double a, b, c, discriminant;

  printf("Enter coeficients a, b, and c:\n");
  scanf("%lf %lf %lf", &a, &b, &c);
  discriminant = b * b - 4 * a * c;

  if (discriminant < 0)
    printf("No roots\n");
  else if (discriminant == 0)
    printf("One root: %f\n", -b/(2*a));
  else 
    printf("Two roots: %f and %f\n",
           (-b + sqrt(discriminant))/(2*a),
           (-b - sqrt(discriminant))/(2*a) );
}   

int main(void) {
  solveQuadraticEquation();  
  printf("Diskriminanten var: %f",  discriminant  );  /* WRONG: discriminant does not exist here */
                                                      /* The compiler finds this error           */
  return 0;
}